Reciprocatory scraper mechanism for frame printing machines



Dec. 9, 1958 A. GlANl 2,863,382

RECIPROCATORY SCRAFER MECHANISM FOR FRAME PRINTING MACHINES Filed Dec. 17, 1957 INVENTOR.

United States Patent RECIPROCATORY SCRAPER MECHANISM FOR FRAME PRINTING MACHINES Adolfo Giani, Bergamo, Italy, assignor to Reggiani Meccanotex S. A., Bergamo, Italy Application December 17, 1957, Serial No. 703,376

3 Claims. (Cl. 101123) This invention has reference to a reciprocatory scraper mechanism suitable for incorporation in frame printing machines for the purpose of squeezing printing ink through a permeable screen which is fixed to and spans a printing frame of the machine.

The principal object of the present invention is to provide an improved oscillatory scraper mechanism which is of simple and economical construction and is eflicient in operation.

Another object of. the invention is to enable the mechanism to make resilient contact with the ink permeable screen so as to minimize the possibility of the said screen being damaged by the mechanism.

Still another object of the invention is to enable the resiliency of the or each screen contacting blade of the mechanism and its angular relationship to the screen when in contact with the latter, to be varied quickly and easily.

A still further object of the invention is to provide a reciprocating mechanismhaving two screen contacting resilient scraper blades and to enable the said blades to be brought into contact with the screen alternatively and automatically at the commencement of successive working strokes of the mechanism, both blades being raised out of contact with the said screen at the termination of each of the said strokes.

In accordance with the said invention, said reciprocatory scraper comprises in combination: a cruciform change-over lever journaled in a pillar adapted for reciprocation transversely of a surface to be scraped; two scrapers connected respectively to one of two lower arms of said change-over lever; a triple armed drivetransmitting lever journaled in said pillar; two arms of said triple armed drive-transmitting lever extending respectively to opposite sides of a stop fixed to and projecting from said pillar; the remaining arm of said triple armed drive-transmitting lever being connected to driving reciprocation means; and elastic connection means between said two arms of said triple armed drive-transmitting lever and the upper arms of said cruciform changeover lever.

In order that the invention may more readily be understood and carried into practice, reference will now be made to the accompanying drawing wherein:

Figure 1 is an elevation, partly in section, showing a scraper mechanism of a frame printing machine in one of two alternative operating positions.

Figure 2 is a similar view to Figure 1 but on a smaller scale and showing the mechanism in an intermediate or neutral non-operating position, and

Figure 3 is a similar view-to Figure 2 but showing the mechanism in the other of its two alternative operating positions.

The scraper mechanism shown in the drawing comprises a pillar or support 1 which is carried by and depends below a support 50 which may consist of the longer arm of a pivoted L-shaped support such as described in the specification of my copending application "ice for Letters Patent No. 703,400 of the same date. The head of the pillar makes sliding engagement with a track or runway 20 provided along the lower edge of the support 50, and the pillar is adapted to be reciprocated lengthwise of the said runway by a chain 26 or equivalent driving member upon pulling the said chain alternatively in the directions of the arrows Fb (Figure 3) and Pa (Figure 1) by any convenient source of reversible tractive power (not shown).

The chain is attached to and extends to opposite sides of the free end 25 of the depending arm 24 of a triple armed drive-transmitting lever which is journalled about a laterally projecting pivot pin 21 provided on and between the ends of the pillar 1. The other two arms 22 and 23 of the triple-armed lever project upwardly from the pivot pin in diverging relationship at an angle which is bisected by the longitudinal centre line of the depending arm to the opposite sides of a stop 15 depending from the pillar head vertically above the pin 21. The said upwardly projecting arms are of the same length which is such that, upon turning the drive transmitting lever about its pivot pin by pulling the driving chain in the appropriate direction, the free end of either arm is adapted to be brought into abutment with the stop whereafter, by continuing to pull the said chain in the same direction, the pillar 1 is traversed along its support 50 as a consequence of endwise displacement of the said chain.

A cruciform change-over lever is journalled about a laterally projecting pivot pin 27 provided on the lower end of the pillar vertically below the pivot pin 21 and the stop 15. The said cruciform lever comprises two downwardly extending diverging arms 28 and 29, and two upwardly extending diverging arms 32 and 33 which project to opposite sides of the triple-armed drive-transmitting lever 22, 23, 24.

A diametrically bored guide 40 projects laterally from, and is rotatable about its axis relatively to the upper and free end of the upwardly projecting arm 32 and a rod 42 extends through and is slidable freely in the bore of the said guide. The end of the rod adjacent the other upwardly extending arm 33 is journalled about a projecting laterally pivot pin 36 provided on and between the root and free end of the arm 22 of the drive-transmitting lever, whereas the opposite end of the said rod is screwthreaded and is engaged by an adjustment nut 44 so that, by rotating the nut about the threaded rod, the degree of compression of a coil spring 54 which is disposed around the rod and of which the opposite end coils seat respectively on the nut and a shouldered sleeve 46, may be varied as desired. The said sleeve is free to slide lengthwise of the rod and is urged by the spring into abutment with the pierced guide 40.

Similarly, the other upwardly extending arm of the change over lever is provided with a diametrically bored guide 41, a rod 35 which is pivoted upon a pin 37 provided on the arm 23 ofthe drive transmitting lever, a nut 45. which engages the threaded end of the rod 35, and a coil spring 55 which is compressed to a predetermined degree between the nut and a shouldered sleeve 47 which is spring urged into abutment with the guide 41.

Each of the downwardly extending and diverging arms 28 and 29 of the change-over lever carries a scraper comprising respectively a body 30 and 31, and a blade Stla and 31a which, by oscillation of the said changeover lever about the pivot pin 27, is adapted to be taken into and out of contact with the upper surface of an ink-permeable screen M spanning a printing frame (not shown) of the machine in which the support 50 is incorporated. A laterally projecting and diametrically bored guide 50 is provided upon the free end of the downwardly extendingarm 28; the bore of the said guide being tapped and engaged by a-bolt 48 of which the shank engages and is rotatable freely in the scraper body 30, relative longitudinal movement between the bolt and body being prevented by providing the shank with a peripheral shoulder 52 which engages and is rotatable io a-complementary annular groove in the body. Similarly, the'scraper body 31 is carried, upon the free end From the above description; it will be appreciated that as the drivetransmitting lever is turned about the pivot pin21by pulling the driving chain in, for example, the direction of the arrowFd to bring the freeend of the arm 23 intoabutrnent with the stop, the rod 35 is displaced longitudinally in the direction which compresses the coil spring "55 with theresult that the said spring, acting'through the sleeve 47 and guide 41, swings the change-over lever about the pivot ,pin 27 in the clockwisedirection which takes the scraper blade 30a into contact with the'screen M, the blade being urged resiliently upon the surface of the screen by the compressed spring, the spring-initiated force urging the scraper into contact with the screen being adjustable by rotation'of the nut 45 upon the rod 43. Moreover, by rotating the bolt 48 within its guide 50, the distance between the operative screen contacting edge of the scraper bar 30a and the said guide may be varied so thatthe said edge is contacted with the screen by a greater or smaller angular displacement of the change over leverthereby varying the angle of inclination of the bar relatively to the surface of the screen. After the scraper blade 30a has contacted'the screen and the arm 23 of 'the drive-transrnitter lever has abutted the stop 15, continued endwise displacement of the chain in the direction of the arrow Fd, traverses the pillar along'the runway 20 and draws the scraper blade 30a over the surface of the screen, in the same direction.

After the mechanism has been traversed through a predetermined distance, the pull exerted on the chain is removed whereupon; since the turning of the drive transmitting lever to take the arm 23, into abutment with the stop has increased the degree of compression of the spring 55*and reduced the degreeof compression of the spring 54, the two levers are subjected to unbalanced and opposed spring-initiated'forces which tend to turn both levers in the reverse direction about theirrespective pivot pins, to the intermediate or neutral inoperative positions shown in Figure 2 wherein both scraper blades 30a and 31a are outof contact with the screen M, the diverging arms 22, 23 of the drive transmitting lever are located out of contact with and symmetrically of the stop 15, and both springs are compressed to the same degree.

To return the scraper mechanism to its alternative operative'position, the driving chain is pulled in the reverse direction as indicated by the arrow Fc, thereby swinging the drive-transmittinglever clockwise about its pivot 21 to'increase the degree of compression of the spring 54, relieve the degree of compression of the spring 55, and take the arm 22 into abutment with the stop 15, the change in thedegrees of compression of the said springs resulting in a spring-initiated clockwise movement of the change-over lever as indicated by the arrow Fb, Figure 3, which takes the scraper bar 31a into resilient contact with the screen. Thereafter, by continuing to pull the chain in the direction of the arrow Po, the pillar is traversed along the runway and the scraper bar 31a is drawn across the surface of the screen, in the direction of the said pull.

Preferably, the nuts 44 and 45'are so adjusted upon their respective rods 42 and 43, that when one of the scraper blades is urged into contact with the screen by its loading spring, the other spring is fully expanded'and unstressed so that it offers no opposing force tending to counteract the effect of the compressed spring. Further,

it is desirable that the nuts should be so adjusted that i when the driving chain is not in tension, they impel the two levers'to positions wherein the scraper blades are spaced equidistantly from the screen, both levers are symmetrical relatively to the pillar, and both springs are partially compressed to the same degree and tend to retain the mechanism in its neutral and inoperative position.

I claim:

1. Rcciprocatory scraper mechanism for frame printing machines comprising in combination: a cruciform change-over lever journaled in a pillar adapted for reciprocation transversely of a surface to be scraped; two scrapers connected respectively to one of two lower arms of said change-over lever; a triple armed drivetransmitting lever journalled in said pillar; two arms of said triple armed drive-transmitting lever extending respectively to opposite sides of a stop fixed to and projecting from said pillar; the remaining arm of said triple armed drive-transmitting lever being connected to driving reciprocation means; elastic connection means between said two arms of said triple armed drive-transmitting lever and the'upper arms of said cruciform change-over lever.

2. Reciprocatory scraper mechanism as claimed by claim 1, wherein said elastic connection means comprise for each upper arm of said change-over lever in combination: a rod pivoted in the adjacent arm of said triple armed drive-transmitting lever and freely traversing a diametrically bored guide pivotally connected to each free-end of an upper arm of cruciform change-over lever; a spring mounted between said diametrically bored, guide and adjusting-means provided on the free end of said rod.

3. Reciprocatory scraper mechanism as claimed by claim 1, wherein inclination adjusting means are provided for *the scraper blade, saidmeans comprising for each lower arm o-f said cruciform change-over lever a diametrically bored guide fixed to and projecting from free'end of lower arm of said cruciform change-over lever; the bore of said guide being tapped and engaged by a bolt; a shouldered portion provided on said bolt; an annular complementary groove in the body of said scraper blade and housing said shouldered portion; the axis of said bolt being different from the axis of said lower arm:

No references cited. 

